This invention relates generally to a railroad wheels, and more specifically to a method to repair worn railroad wheels to enable them to be returned to service.
During service, railroad wheels wear away, as they are designed to be sacrificial relative to the railroad tracks. Additionally, wheels can be removed for other defects such as spalling, shelling, and out-of-roundness.
When a wheel is removed from service for tread defects, it may be re-machined to adjust its profile relative to the rail geometry, provided that there is sufficient rim metal remaining. Presently, the most common reason that wheels are discarded is because of wearing to a minimum dimension.
Weld build-up or fusion welding of a new ring to the wheel hub is prohibitive because of tight quality standards imposed on rail wheels by the Association of American Railroads (AAR). Currently there are no good repair techniques for rail wheels due to restrictions on inclusions or cracks that would generally result from traditional welding techniques.
One non-welding approach taken to address the wear problem has been to shrink fit a new steel ring onto the wheel hub using thermal expansion techniques. However, a disadvantage to this approach is that the ring or “tire” is under tension in service, and as it wears thinner it becomes highly vulnerable to cracking.
Wheels are a high-cost item for rail operators. Accordingly it would be desirable to have a repair method for extending the service life of worn railroad wheels that also meets stringent safety requirements.